Countries where basements are or were normal (Germany Canada USA etc) tend to insulate at least the wall (in energy-efficient buildings they insulate the floor). Ideally on the outside of the wall, but do provide protection from vermin eating it (seriously, this does happen).
In calculating a floor U-value of 0.3, I wonder what soil thermal conductivity was assumed (dry sand or gravel, wet clay, other). Did it take account of rainwater draining down and carrying away heat from the floor edge?
In most other buildings, a wall U-value of 0.7 would be considered poor - it hasn't met the UK Building Regs since about 1982. I suppose of course you might heat such a room electrically; i.e., by having inefficient electrical appliances and office equipment, but how sensible is this in the long run?